The use of metal halides to generate high metallic densities at reduced operating temperatures for high energy metal vapor lasers is described in detail in U.S. Pat. No. 3,934,211, issued Jan. 20, 1976, entitled, "Metal Halide Vapor Laser," assigned to the assignee of the present invention, and incorporated herein by reference.
Pulsed laser action at the copper 5106A and 5782A wavelengths has been obtained from discharges through copper iodide: argon mixtures at approximately 600.degree. C. Preliminary experiments in static gases reveal that two electrical discharge pulses, separated by between 50 and 250 microseconds, are required to produce a laser output. The first electrical pulse produces substantially copper iodide dissociation but little laser output, whereas a second, high current pulse excites the dissociated copper atoms and produces substantial laser output. The 50 microsecond minimum delay time required between pulses is believed to be caused by the creation of copper atoms in the lower laser level (lll) at the time of molecular dissociation. While initially it is difficult to pump a population inversion with respect to the lower laser level population, after approximately 50 microseconds, most of the excited metastable atoms are converted to ground state copper atoms through diffusion to the walls of the laser apparatus, or due to a bulk effect within the medium. At this point, the second excitation pulse can easily excite population inversions, similar to that of the pure copper vapor laser. After approximately 250 microseconds delay, however, the copper atoms recombine with iodine to form copper iodide once again and the double pulse sequence must be repeated to obtain further laser pulses. Thus diffusion times determine the minimum pulse separation, and recombination times determine the maximum pulse separation.
These physical processes place limits upon the laser pulse repetition rates available in static metal halide lasers.